The performance and coverage of a wireless communication system (e.g., a code division multiple access system (CDMA)) may be dependent upon the amount of interference in a relevant frequency band. Sources of interference may include the wireless communication system itself, external sources of electromagnetic energy, geological formations such as mountains, and/or man made objects such as buildings.
For example, transmission of information (e.g. voice and/or data) from mobile stations, on a reverse link, or from a base station, on a forward link may generate undesirable interference. Interference at a base station of a wireless system may reduce reverse link coverage and/or reliability. Accordingly, a base station may improperly drop a call of a subscriber station, a subscriber station may experience low voice quality or a high frame error rate, or a subscriber station may have an increased access failure rate.
As is well-known in the art, accurate and updated estimations of noise floor values are important in the accurate and updated estimations of the rise in receive strength indications (e.g. RSSI rise or rise over thermal (ROT)), for a given link (e.g. a reverse link). Further, the accurate estimation of a receive strength indication rise (e.g., RSSI rise or rise over thermal (ROT)) may be important in understanding system loading and, further, in controlling a wireless communications system.
Current empirical noise floor values may differ, or substantially differ, within a wireless communication system (e.g., within cells of a wireless communication system) as a result of, for example, hardware variations, differences in surroundings, the presence of an interferer or jammer, etc. Further, current empirical noise floor values may also differ, or substantially differ, in a plurality of diversity receive paths of an individual cell due to different received path gains. Further still, current empirical noise floor values may vary with current system loading, which may vary with time.
As is well known in the art, conventional wireless communication systems, an example of which is illustrated in FIG. 1, utilizes a hard-coded noise floor value as an initial value. This initial noise floor value is used by the wireless communications system for twenty-four hours and is updated to a new value in any well-known manner, only at the end of a twenty-four hour period.
This presents a problem in the control of a wireless communications systems in that the noise floor for the first twenty four hours, i.e., the hard coded noise floor, may be different, or substantially different, than the actual current noise floor value for a given time and/or location within a wireless communication system. Accordingly, a need exists for a faster more accurate estimation of the noise floor and rise over thermal (ROT).